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    SubjectRe: [RFC PATCH 0/6] Do not call ->writepage[s] from direct reclaim and use a_ops->writepages() where possible
    On Tue, Jun 15, 2010 at 03:13:09PM -0400, Rik van Riel wrote:
    > On 06/15/2010 12:54 PM, Christoph Hellwig wrote:
    > >On Tue, Jun 15, 2010 at 12:49:49PM -0400, Rik van Riel wrote:
    > >>This is already in a filesystem. Why does ->writepage get
    > >>called a second time? Shouldn't this have a gfp_mask
    > >>without __GFP_FS set?
    > >
    > >Why would it? GFP_NOFS is not for all filesystem code, but only for
    > >code where we can't re-enter the filesystem due to deadlock potential.
    > Why? How about because you know the stack is not big enough
    > to have the XFS call path on it twice? :)
    > Isn't the whole purpose of this patch series to prevent writepage
    > from being called by the VM, when invoked from a deep callstack
    > like xfs writepage?
    > That sounds a lot like simply wanting to not have GFP_FS...

    buffered write path uses __GFP_FS by design because huge amounts
    of (dirty) memory can be allocated in doing pagecache writes. If
    would be nasty if that was not allowed to wait for filesystem

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      Last update: 2010-06-16 09:59    [W:0.019 / U:31.280 seconds]
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